NIST

NIST¤Ç¤ÏBLEU¤ÈƱÍͤ˸ì½ç(5-gram)¤ÎÀµ¤·¤µ¤ÇÈæ³Ó¤ò¹Ô¤¦¤¬¡¤BLEU¤È¤Ï¾ðÊóÎ̤ˤè¤Ã¤Æ½Å¤ßÉÕ¤±¤ò¤·¤Æ¤¤¤ëÅÀ¤¬°Û¤Ê¤ë¡¥¤Þ¤¿¡¤¥Ú¥Ê¥ë¥Æ¥£´Ø¿ô¤¬°Û¤Ê¤Ã¤Æ¤ª¤ê¡¤NIST¤ÎÊý¤¬Ê¸Ä¹¤ò¹Íθ¤¹¤ë¥Ú¥Ê¥ë¥Æ¥£¤¬²Ý¤»¤é¤ì¤ë¡¥ NIST¤Ï°Ê²¼¤Î¼°¤Ç·×»»¤µ¤ì¤ë¡¥

$$NIST_{score} = BP \times \sum_{N=1}^N \frac{\displaystyle\sum_i \... ...playstyle\sum_i \mbox{½ÐÎÏʸ{\it i}¤ÈÀµ²òʸ{\it i}¤Ç°ìÃפ·¤¿{\it N}-gram¤Î¿ô} }$$ (6.4)

$$Info_i \left( w_1 ... w_n \right) = \log_2 \frac{ɾ²Á¥³¡¼¥Ñ¥¹Ãæ \... ...w_1 ... w_{n-1} \right)¤Î¿ô}{ɾ²Á¥³¡¼¥Ñ¥¹Ãæ¤Î \left( w_1 ... w_n \right) ¤Î¿ô }$$ (6.5)

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